12 



UNIV. OF N. H. AGR. EXPERIMENT STATION 



[Bulletin 240 



when in the respiration chamber as nearly as possible the same as those 

 which prevail in the metabolism stalls. No change has, however, been 

 made affecting the principle of ventilation or its theory. The chamber 

 was originally designed for the purpose of carrying out experiments of 

 two to four hours' duration, without regard to measurement of the visible 

 excreta; but with the above changes an experiment may now be extended 

 to any desirable length of time. 



The respiration chamber consists of a rugged framework of 4" x 4" 

 spruce enclosed by a sheet metal shell open at the rear end for entry of the 



animal, this opening being closed by a 

 double set of doors when the chamber is 

 in use. The details of this frame and 

 door construction have been described in 

 Bulletin 16 of this Station. A four-inch 

 space provided between the double set of 

 doors serves as a reservoir for fresh out- 

 door air supplied by a blower outside of 

 the building. The inside door is pressed 

 against a felt surface which is somewhat 

 porous; hence when air is removed from 

 the chamber to supply the absorbing ap- 

 paratus there will be a proportional seep- 

 age into the chamber from this fresh air 

 reservoir, as the contact between door 

 and felt is the only part of the chamber 

 that is not absolutely sealed. 



A framework of metal steam pipes 

 (Plate 1), allows free circulation of the 

 air in the chamber. A steel swivel stan- 

 chion gives the animal a reasonable 

 amount of freedom of movement, and 

 eliminates any irksome restraint that 

 causes nervousness. The floor is heavily 

 padded and thus restful in the standing 

 position and favors longer lying periods. 

 Feed box and water are conveniently 

 placed so that during experiments of from 

 one to five days' duration, as now con- 

 ducted, the conditions of existence in the 

 chamber are comparal)le to those main- 

 tained in a modern dairy barn, except for 

 periodical exercise and daylight. The 

 lack of exercise is partly compensated 

 by the floor padding, which relieves mus- 

 cular strain. Perhaps it may be advis- 

 able to install a substitute for sunlight to 

 approximate greater daily normalcy for 

 long experiments. At present the cham- 

 ber is lighted by electricity, controlled 

 from the outside. 



Figure 4 — Details of mechanism for 

 feeding and watering animal in respi- 

 ration chamber 



Above — Floor plan. Below — ^side el- 

 evation. C, crank to raise shutter D; 

 g, groove for water seal for removable 

 cover b ; h, handles to feed box ; B , crank 

 to move chain d to shift feed box. 

 Water supply tanks W and w; p, spool 

 on shaft operated by crank; S, scales. 

 K, sprockets on chain H which moves 

 feed^box, F. 



